U.S. patent number 4,616,616 [Application Number 06/527,043] was granted by the patent office on 1986-10-14 for fuel control system.
This patent grant is currently assigned to Caterpillar Inc.. Invention is credited to Michael E. Moncelle, Robert E. Samuelson, Waldema A. Staniak.
United States Patent |
4,616,616 |
Staniak , et al. |
October 14, 1986 |
**Please see images for:
( Certificate of Correction ) ** |
Fuel control system
Abstract
A fuel control system (10 or 70) includes a hydraulic servo
system (17) for moving a fuel rack (15) in response to movement of
a rack control member (16). A brushless direct current torque motor
(50), having a rotor (51) and a control lever (53) fixed thereto,
is arranged with its lever end (54) confined between opposed
shoulders (41, 42) on the rack control member (16). Electronically
energized movement of the rotor (51) and its control lever (53) in
one direction, or spring (56) biased movement in the other, causes
corresponding movement of the control member (16) and fuel rack
(15). A second control lever (99), movable by a mechanical governor
control (80), is engageable with another shoulder (104) on the rack
control member (16) to move it in a fuel-decreasing direction. The
present fuel control systems (10 and 70) are particularly useful in
conjunction with a fuel injection pump (11) for a diesel engine
(13) with the fuel flow rate being controlled in sole response (10)
to an electronic engine control (60) or in dual response (70) to an
electronic engine control (60) and a mechanical governor control
(80).
Inventors: |
Staniak; Waldema A. (Geneva,
CH), Samuelson; Robert E. (Washington, IL),
Moncelle; Michael E. (Normal, IL) |
Assignee: |
Caterpillar Inc. (Peoria,
IL)
|
Family
ID: |
24099867 |
Appl.
No.: |
06/527,043 |
Filed: |
August 29, 1983 |
Current U.S.
Class: |
123/357; 123/365;
123/373 |
Current CPC
Class: |
F02D
41/38 (20130101); F02D 1/12 (20130101); F02D
1/08 (20130101); F02B 3/06 (20130101) |
Current International
Class: |
F02D
1/08 (20060101); F02D 1/12 (20060101); F02D
41/38 (20060101); F02B 3/00 (20060101); F02B
3/06 (20060101); F02M 039/00 () |
Field of
Search: |
;123/357,358,359,372,373,365 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
8216800 |
|
Apr 1983 |
|
FR |
|
1091453 |
|
Nov 1967 |
|
GB |
|
1400299 |
|
Jul 1975 |
|
GB |
|
2051416 |
|
Jan 1981 |
|
GB |
|
Other References
Technical Bulletin No. EG 40-2--American Bosch, Feb. 1978. .
Parts Catalog--Aeroflex Laboratories, Inc., Jul. 1973. .
Motortechnische Zeitschrift--No. 42, pp. 323-324, Sep.
1981..
|
Primary Examiner: Miller; Carl Stuart
Attorney, Agent or Firm: Phillips, Moore, Lempio &
Finley
Claims
We claim:
1. A fuel control system (70) comprising:
a fuel rack (15) movable in opposite fuel-increasing and
fuel-decreasing directions;
a rack control member (16) movable in opposite fuel-increasing and
fuel-decreasing directions;
servo system means (17) for moving said fuel rack in response to
movement of said rack control member (16);
an electrically energizable member (51) movable in opposite
fuel-increasing and fuel-decreasing directions, said electrically
energizable member (51) being urged to move in its fuel-decreasing
direction when energized;
first coupling means (52) for connecting said electrically
energizable member (51) to said rack control member (16) to move
said rack control member (16) in its fuel-decreasing direction in
response to movement of said electrically energizable member (51)
in its fuel-decreasing direction;
a mechanical governor control (80) having a member (90) movable in
opposite fuel-increasing and fuel-decreasing directions;
second coupling means (98) for connecting said mechanical governor
(80) to said rack control member (16) to move said rack control
member (16) in its fuel-decreasing direction in response to
movement of said mechanical governor member (90) in its
fuel-decreasing direction, said second coupling means having the
further functions of allowing the position of said rack control
member (16) to be controlled solely by said electrically
energizable member (51) when said electrically energizable member
(51) has been urged to move by the energization thereof to a
position calling for less fuel than the position of said mechanical
governor member (90), and of enabling the position of said rack
control member (16) to be controlled by said mechanical governor
member (90) when said mechanical governor member (90) is at a
position calling for less fuel than the position to which said
electrically energizable member (51) has been urged by the
energization thereof;
bias means (55) for biasing said rack control member (16) to move
in its fuel-increasing direction.
2. A fuel control system (70) as set forth in claim 1, wherein said
rack control member (16) has first and second shoulders (41, 104)
thereon both facing in the direction of fuel-increasing movement of
the rack control member (16), wherein said first coupling means
(52) includes a first control lever (53) movable by said
electrically energizable member and having an end (54) engageable
with said first shoulder (41), and wherein said second coupling
means (104) includes a second control lever (99) movable by said
mechanical governor member (90) and having an end (103) engageable
with said second shoulder (104).
3. A fuel control system (70) as set forth in claim 2 wherein said
rack control member (16) has a third shoulder (42) spaced from and
facing said first shoulder (41), and wherein said end (54) of said
first control lever (53) is confined between said first and third
shoulders (41, 42).
4. A fuel control system (70) as set forth in claim 2 wherein said
second coupling means (98) has the further function of holding said
rack control member (16) against being moved in its fuel-increasing
direction by said bias means (55) when said second control lever
(99) is in engagement with said second shoulder (104) on said rack
control member (16).
5. A fuel control system (70) as set forth in claim 1 and further
including:
electronic control means (60) for energizing said electrically
energizable member (51),
means (85, 87) for limiting movement of said movable member (90) of
said mechanical governor control (80) in a fuel-increasing
direction upon deenergization of said electronic control means
(60).
6. A fuel control system (70) as set forth in claim 1 wherein said
electrically energizable member (51) is the rotor of a brushless
torque motor (50).
7. A fuel control system (70) as set forth in claim 6, wherein said
rack control member (16) has first and second shoulders (41, 104)
both facing in the direction of fuel-increasing movement of said
rack control member (16), wherein said first coupling means (52)
includes a first control lever (53) fixed to said rotor (51) and
having an end (54) engageable with said first shoulder (41), and
wherein said second coupling means (98) includes a second control
lever (99) movable by said mechanical governor member (90) and
having an end (103) engageable with said second shoulder (104).
8. A fuel control system (70) as set forth in claim 7 wherein said
rack control member (16) has a third shoulder (42) spaced from and
facing said first shoulder (41) thereon, and wherein said end (54)
of said first control lever (52) is confined between said first and
third shoulders (41, 42).
9. A fuel control system (70 as set forth in claim 7 wherein said
second coupling means (98) has the further function of holding said
rack control member (16) against being moved in a fuel-increasing
direction by said bias means (55) when said second control lever
(99) is in engagement with said second shoulder (104) of said rack
control member (16).
10. A fuel control system (70) as set forth in claim 6 and further
including:
electronic control means (60) for energizing said rotor of said
torque motor (51);
means (85, 87) for limiting movement of said movable member (90) of
said mechanical governor control (80) in a fuel-increasing
direction upon deenergization of said electronic control means
(60).
11. A fuel control system (10 or 70) comprising:
a fuel rack (15) movable in opposite fuel-increasing and
fuel-decreasing directions;
a rack control member (16);
servo system means (17) for moving said fuel rack (15) in response
to movement of said rack control member (16) and with a force
greater than that required to move said rack control member (16),
said rack control member (16) being mounted on the servo system
means (17) for limited axial sliding movement in opposite
fuel-increasing and fuel-decreasing directions;
an electrically energizable brushless torque motor (50) having a
rotor (51) movable in opposite fuel-increasing and fuel-decreasing
directions, said rotor (51) being urged to move in one of its
directions upon energization of said motor (50);
coupling means (52) for connecting said rotor (51) to said rack
control member (16) to move said rack control member (16) in one of
its directions in response to movement of said rotor (51) in its
corresonding direction;
spring means (37) connected between the rack control member (16)
and the servo system means (17) for resiliently providing relative
movement between the servo system means (17) and the rack control
member (16) whenever the rack control member (16) assumes a
stationary fuel delivery position and the servo system mean (17) is
moved in its fuel-decreasing direction;
bias means (55) for biasing said rack control member (16) to move
in a direction opposite to the direction that said coupling means
(52) will move said rack control member (16) when said torque motor
(50) is energized;
sensor means (62) for sensing the position of said fuel rack
(15);
electronic control means (60) for energizing said torque motor (50)
with sufficient force to balance the force of said bias means (55)
when said sensor means (62) senses that said fuel rack (15) is at a
desired position; and,
fuel shutoff means (66 or 71) for directly moving the servo system
means (17) and the fuel rack (15) to a fuel shutoff position.
12. A fuel control system (10) as set forth in claim 11, wherein
said rotor (51) of said torque motor (50) is urged to move in its
fuel-increasing direction when said torque motor (50) is
electrically energized and wherein said bias means (55) biases said
rack control member (16) in its fuel-decreasing direction.
13. A fuel control system (70) as set forth in claim 11 and further
including:
a mechanical governor control (80) having a member (90) movable in
opposite fuel-increasing and fuel-decreasing directions;
a second coupling means (98) for connecting said mechanical
governor member (90) to move said rack control member (16) in its
said one direction in response to movement of said mechanical
governor member (90) in its corresponding direction.
14. A fuel control system (70) as set forth in claim 13, wherein
said rotor (51) of said torque motor (50) is urged to move in its
fuel-decreasing direction when said torque motor (50) is
electrically energized and wherein said bias means (55) biases said
rack control member (16) in its fuel-increasing direction.
15. A fuel control system (70) comprising:
a fuel rack (15) movable in opposite fuel-increasing and
fuel-decreasing directions;
a rack control member (16) movable in opposite fuel-increasing and
fuel-decreasing directions and having first and second shoulders
(41,104) thereon and facing in the same direction;
servo system means (17) for moving said fuel rack (15) in response
to movement of said rack control member (16) and with a force
greater than that required to move said rack control member
(16);
an electrically energizable brushless torque motor (50) having a
rotor (51) movable in opposite fuel-increasing and fuel-decreasing
directions, said rotor (51) being urged to move in one of its
directions upon energization of said motor (50);
a first control lever (53) fixed to said rotor (51), said first
control lever (53) having an end (54) engageable with said first
shoulder (41) on said rack control member (16) to move said rack
control member (16) in one of its directions in response to
movement of said rotor (51) in its corresponding direction;
a mechanical governor control (80) having a member (90) movable in
opposite fuel-increasing and fuel-decreasing directions;
a second control lever (99) actuated by said mechanical governor
member (90), said second control lever (99) having and end (103)
engageable with said second shoulder (104) on said rack control
member (16) to move said rack control member (16) in its said one
direction in response to movement of said mechanical governor
member (90) in its corresponding direction.
16. A fuel control system (70) as set forth in claim 15, including
coupling means (98) for enabling said end (103) of said second
control lever (99) and said second shoulder (104) on said rack
control member (16) to be moved away from each other.
17. A fuel control system (70) as set forth in claim 15 and further
including bias means (55) for biasing said rack control member (16)
to move in a direction opposite to the direction that said first
control lever (53) will move said rack control member (16) when
said torque motor (50) is energized.
18. A fuel control system (70) as set forth in claim 17, and
further including:
sensor means (62) for sensing the position of said fuel rack
(15);
electronic control means (60) fr energizing said torque motor (50)
with sufficient force to balance the force of said bias means (55)
when said sensor means (62) senses that said fuel rack (15) is at a
desired position.
19. A fuel control system (70) as set forth in claim 18, wherein
said rotor (51) of said torque motor (50) is urged to move in its
fuel-decreasing direction when said torque motor (50) is
electrically energized and wherein said bias means (55) biases said
rack control member (16) in its fuel-increasing direction.
20. The fuel control system (10 or 70) of claim 11 wherein the
servo system means (17) includes a piston (19) connected to the
fuel rack (15) and a pilot valve spool (21) mounted within the
piston (19) for limited axial movement relative thereto, said rack
control member (16) being mounted for limited axial sliding
movement on the pilot valve spool (21).
21. The fuel control system (10 or 70) of claim 11 wherein the rack
control member (16) defines a shoulder (41) thereon and the
coupling means (52) includes a control lever (53) fixed to the
rotor (51) of the torque motor (50) and having a free end (54)
engageable with the shoulder (41) of the rack control member
(16).
22. The fuel control system (10 or 70) of claim 11 wherein said
sensor means (62) has the function of directly sensing the actual
position of said fuel rack (15).
Description
DESCRIPTION
1. Technical Field
This invention relates to fuel control systems wherein a fuel
injection pump delivers fuel to a diesel engine and more
particularly to the actuating mechanism for moving the fuel rack of
the fuel injection pump and maintaining it at a desired fuel
delivery position.
2. Background Art
The operation of a diesel engine is controlled basically by varying
the amount of fuel delivered to the engine by the fuel injection
pump and by setting the time of fuel injection into the combustion
cylinders relative to the time that the engine pistons reach top
dead center during their compression strokes. In general, the
amount of fuel injected into the combustion cylinders will control
the speed of the engine and the time of injection will affect the
efficiency of fuel combustion and engine operation.
In a fuel control system for a diesel powered engine, the fuel
injection pump typically includes a movable fuel rack whose
translational position determines the amount of fuel injected per
stroke of the fuel injection pump, the fuel rack being under the
control of a governor system which includes an operator-controlled
throttle that enables the vehicle operator to change engine speed
within the preset low-idle and high-idle limits and includes a
mechanism responsive to engine speed which will automatically
increase fuel injection to produce more power and increase the
engine speed when an increased vehicle load causes the engine speed
to decrease or vice versa.
If the governor system allows too much fuel to be injected during
an engine piston stroke, causing incomplete fuel combustion, as may
occur when the vehicle operator quickly increases the throttle
setting, a considerable amount of smoke and emissions may be
present in the engine exhaust which exceed the smoke and emission
standards set by federal and/or state governments.
In order to meet the smoke and emission standards, electronic
engine controls have been and are being developed which monitor
changing engine conditions and determine from such conditions the
instantaneous optimum allowable amount of fuel to be injected into
the engine. Such controls generate electrical signals to be used in
moving the fuel rack to the correct position and in maintaining the
fuel rack at such position.
A problem presently exists in providing a mechanism which will be
energized by such electrical signals from an electronic engine
control and which will move the fuel rack in response to such
electrical energization.
It may be also desirable to provide a fuel control system wherein a
fuel rack is jointly controlled by an electronic engine control and
by a conventional throttle actuated mechanical governor. For
example, an electronic engine control may be designed as a rack
limit control, allowing the fuel rack to be controlled in response
to a conventional mechanical governor as long as the position of
the fuel rack is below the allowable limit determined by the
electronic engine control. In such case, the system will function
so that the electronic engine control takes over and prevents the
mechanical governor from moving the fuel rack beyond such
limit.
Or, the electronic engine control may be designed for primary
actuation of the fuel rack, with the mechanical governor
controlling the limits of engine speed and preventing the
electronic engine control from moving the fuel rack beyond such
limits.
A problem presently exists in providing a fuel control system which
provides easy and smooth movement and positioning of the fuel rack
when independently controlled by an electronic engine control and
by a mechanical governor, with control of the fuel rack alternating
back and forth from one control to the other as needed.
A further problem exists in providing a fuel control system which
will readily enable the fuel rack to be actuated in response to a
mechanical governor control up to a rack limit set by an electronic
engine control or which will enable the fuel rack to be actuated in
response to an electronic engine control up to a speed limit set by
a mechanical governor control.
Another problem exists in providing a fuel control system which is
compatible with existing mechanical governing mechanisms and which
will allow easy conversion of an existing fuel control system
having a mechanical governing system to a fuel control system
having a mechanical and electronic dual control of rack
movement.
A further problem exists in providing a fuel control system which
will cause movement of the fuel rack to shut off fuel flow in the
event of failure of the electronic engine control when such control
is used alone for fuel rack control.
Another problem exists in providing a fuel control system utilizing
a joint control by an electronic engine control and a mechanical
governor control which will allow limp-home control of the fuel
rack by the mechanical governor control, but at a reduced fuel
delivery position, in the event of failure of the electronic engine
control.
DISCLOSURE OF THE INVENTION
The present invention is directed to overcoming one or more of the
problems set forth above.
In one aspect of the invention, a fuel control system is provided
having a movable fuel rack, a movable rack control member, a servo
system for moving the fuel rack in response to movement of the rack
control member, a brushless torque motor having a rotor which will
rotate in response to electrical energization and a coupling means
for connecting the rotor to the rack control member for movement of
the rack control member by the rotor of the torque motor.
In a further aspect of the invention as just described, the torque
motor is arranged to move the rack control member in a
fuel-increasing direction in response to electrical energization,
and a bias means is provided to bias the rack control member in a
fuel-decreasing direction.
In another aspect of the invention, a dual-controlled fuel system
is provided having a movable fuel rack, a movable rack control
member, and a servo system for moving the fuel rack in response to
movement of the rack control member. In this fuel system, an
electronic engine control and a mechanical governor control are
provided, each having a member movable independently of each other
in fuel-increasing and fuel-decreasing directions. First and second
coupling means connect the movable members of the electronic engine
control and mechanical governor control to the rack control member
for movement thereof.
In a further aspect of the invention, the above described
dual-controlled fuel system is arranged so that which ever movable
member of the electronic engine control or the mechanical governor
control is calling for the least fuel delivery position of the fuel
rack will act on the rack control member to move the fuel rack to
said least position, while the other movable member acts
independently for limiting movement of the fuel rack in a
fuel-increasing direction.
Yet another dual-control aspect of the invention is that the
movable member of the electronic engine control will, when
electrically energized, urge the rack control member in a
fuel-decreasing direction, with a bias means being provided to urge
the rack control member to move in a fuel-increasing direction. In
event of failure of the electronic engine control, the bias means
will enable the rack control member to be controlled solely by the
movable member of the mechanical governor control and a limit means
is provided to limit movement of the movable member of the
mechanical governor control in a fuel-increasing direction upon
such failure of the electronic engine control.
The foregoing and other aspects will become apparent from the
following detailed description of the invention when considered in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1, partly in block diagrammatic form and partly in sectional
detail, illustrates a fuel control system and rack control member
thereof utilizing the present invention and wherein the rack
position is controlled solely by an electronic engine control.
FIG. 2, partly in block diagrammatic form and partly in sectional
detail, illustrates a fuel control system and rack control member
thereof and wherein the rack position is controlled alternately by
an electronic engine control or a mechanical governor control.
FIG. 3 is a detail of FIG. 2 illustrating the position of parts of
the mechanical governor control during normal operation.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the embodiment of the invention shown in FIG. 1,
the fuel control system 10 includes a fuel injection pump 11 for
pressurizing and metering the amount of fuel delivered from a fuel
tank 12 to the combustion cylinders of an internal combustion
engine 13. As is conventional, the fuel injection pump 11 includes
a fuel injection pump housing 14 and a reciprocating fuel rack 15
which is axially movable in opposite fuel-increasing and
fuel-decreasing directions (shown in FIGS. 1, 2 and 3 as being to
the left and to the right, respectively).
The fuel control system 10 further includes a rack control member
16 which is movable in opposite fuel-increasing and fuel-decreasing
directions. In the particular system illustrated herein, the rack
control member 16 is in the form of an annular sleeve or collar. A
hydraulic servo system 17 is further provided to function as a
means for moving the fuel rack 15 in its fuel-increasing and
fuel-decreasing directions in response to corresponding
fuel-increasing or fuel-decreasing movements of the rack control
member 16 and with a force greater than that required to move the
rack control member 16. The hydraulic servo system 17 particularly
illustrated herein includes a cylinder 18, a piston 19, a sleeve 20
and a pilot valve spool 21.
The cylinder 18 is secured to the fuel injection pump housing 14
and has a passage 22 communicating with the interior of the pump
housing 14 through which pressurized engine lubricating oil may
flow. The piston 19, which is ported and stepped and connected to
the fuel rack 15 for axial movement therewith, is disposed for
axial movement in the cylinder 18. The diameter of the left end 23
of the piston 19 is less than the diameter of the right end 24 of
the piston which slides in the sleeve 20 fixed within the cylinder
18, and both such diameters are less than that of the intermediate
piston head 25. The left end 23 of the piston, the piston head 25
and the cylinder 18 define an annular chamber 26. The piston head
25 has an annular surface 27 on the right side thereof.
The pilot valve spool 21 is mounted within the piston 19 for
limited axial movement relative thereto, the pilot valve spool 21
having a reduced diameter recess 29 in continuous communication
with piston ports 31. The axial length of recess 29 is sized
relative to piston ports 32 and 33 such that recess 29 does not
communicate with either of the piston ports 32 or 33 when the pilot
valve spool 21 is in the balanced position of FIG. 1, but will
communicate with the piston ports 32 or 33 when moved to the right
or the left respectively relative to the piston 19.
The rack control member 16 is mounted for limited axial sliding
movement on the left end stem 36 of the pilot valve spool 21. The
rack control member 16 is biased towards the right by a spring 37
which shoulders against a spring retainer 38, with rightward
movement of the rack control member 16 being limited by a retainer
clip 39 which is fixed to the pilot valve spool stem 36. The rack
control member 16 has a pair of radially extending flanges on one
side thereof to provide a pair of oppositely facing shoulders 41
and 42.
An electrically energizable brushless direct current torque motor
50 is mounted in fixed relation to the cylinder 18 of the servo
system 17, the motor 50 having a rotatable rotor 51 movable in
opposite fuel-increasing and fuel-decreasing directions. It is a
functional characteristic of such a torque motor that its rotor
will turn freely in its bearings when no electrical current is
supplied to the motor. When electrical current is applied, the
rotor will exert a preselected torque in one direction, the degree
of torque being proportional to the amount of the current applied.
A "brushless direct current torque motor" is also known as a
"proportional rotary solenoid," or a "proportional rotary
actuator."
A coupling means 52 is provided for connecting the rotor 51 of the
torque motor 50 to the rack control member 16 to move the rack
control member 16 in one of its fuel-increasing or fuel-decreasing
directions in response to movement of the rotor 51 in its
corresponding fuel-increasing or fuel-decreasing direction. In the
particular system shown herein, the coupling means 52 comprises a
control lever 53 fixed to the rotor 51 and having a free end 54
confined between the shoulders 41 and 42 of the rack control member
16.
In the system illustrated in FIG. 1, the torque motor 50 is
arranged so that current applied thereto will cause a torque to be
exerted on the control lever 53, urging it to move in a clockwise,
fuel-increasing direction, in turn urging the rack control member
16 in its leftward, fuel-increasing direction. A bias means 55 is
provided for biasing the rack control member 16 in a direction
opposite to the direction that the coupling means 52 will move the
rack control member 16 when the torque motor 50 is energized. In
the particular fuel control system 10 shown in FIG. 1, the bias
means 55 comprises a low rate compression spring 56 confined
between a fixed spring seat 57 and an extension 58 of the control
lever 53. With this arrangement, the spring 56 biases control lever
53 in its fuel-decreasing direction, with the free end 54 of
control lever 53 acting on the shoulder 41 of the rack control
member 16 to bias such rack control member 16 for movement in its
fuel-decreasing direction.
The fuel control system 10 of FIG. 1 also includes an electronic
engine control 60 which processes information from the engine
operation sensors 61, the rack position sensor 62, and throttle
position sensor 63, and generates a rack control signal which is
applied to torque motor 50. For example, the engine operation
sensors 61 may monitor engine speed, fuel injection timing angle,
atmospheric pressure, lubricating oil pressure, fuel temperature,
coolant temperature, atmospheric temperature, and intake manifold
or boost pressure. The rack position sensor 62 may be in the form
of a potentiometer having its wiper arm driven by fuel rack
movement or, alternatively the rack position sensor 62 may be an
induction-type transducer. The throttle position sensor 63 may be
in the form of a potentiometer having its wiper arm driven by
movement of a foot-actuated throttle pedal 64.
Since the particular design of the electronic engine control 60
forms no part of the present invention, the specific details
thereof have not been shown. As far as the present disclosure is
concerned, it is necessary only that such electronic engine control
60 output a predetermined level of current to torque motor 50 to
move the rack control member 16 to a desired position which is
balanced by the spring 56.
A shut-down solenoid 65 and pivotal lever 66 are mounted in
operational relation to the hydraulic servo system 17 so that the
solenoid plunger can engage one end 67 of the pivotal lever 66, the
other end 68 of the pivotal lever 66 being engageable with the stem
36 of the pilot valve spool 21. The solenoid 65 is arranged so that
during normal engine operation, the solenoid 65 is energized and
its plunger is retracted to the right. When the solenoid is
deenergized, an internal spring (not shown) will move the plunger
to the left, as indicated by the arrow, to engage lever end 67 so
that lever 66 will pivot in a clockwise direction to cause pilot
valve spool 21 to move in a fuel-decreasing direction. Shaft 69, on
which lever 66 is fixed, may be manually rotated in a clockwise
direction to provide a manual fuel shut-down capability.
The fuel control system of FIG. 2 uses the same hydraulic servo
system 17 to cause movement of the fuel rack 15 in response to
movement of the rack control member 16 as described above, but
utilizes a combined operation of an electronic engine control and a
mechanical governor control to set the position of the fuel rack
15.
The electronic portion of the fuel control system 70 of FIG. 2 is
generally similar to the electronic portion of the fuel control
system 10 of FIG. 1, in that the rotor 51 of the brushless torque
motor 50 is movable in opposite fuel-increasing and fuel-decreasing
directions and is urged to move in one of its directions upon
energization of the torque motor 50, and the coupling means 52
connects the rotor 51 of the torque motor to the rack control
member 16 to move the rack control member in one of its
fuel-increasing or fuel-decreasing directions in response to
movement of the rotor 51 in its corresponding fuel-increasing or
fuel-decreasing direction. Likewise, the bias means 55 functions to
bias the rack control member 16 to move in a direction opposite to
the direction that the coupling means 52 will move the rack control
member 16 when the torque motor 50 is energized.
The electronic portion of the fuel control system 70 of FIG. 2
differs from that previously described in connection with FIG. 1 in
that the electronic engine control 60 of FIG. 2 is programmed so
that an energizing signal applied to the torque motor 50 will urge
its rotor 51 and lever arm 53 to rotate in a counterclockwise,
fuel-decreasing direction, against the bias force of the bias means
55 and spring 56 thereof, the latter being arranged to bias lever
arm 53 in a clockwise, fuel-increasing direction.
A manually-operable fuel shut-down lever 71, rotatable about the
axis of shaft 72, is provided to engage the end of pilot valve
spool 21 and move it to the right when it is desired to shut off
fuel flow to engine 13. Preferably, a shut-down solenoid 73 is
mounted on governor housing 74 with its plunger 75 being in the
path of movement of shut-down lever 71. Solenoid 73 is energized
during normal engine operation so that its plunger 75 is moved to
the left and held out of the way of normal movement of the pilot
valve spool 21. In the event of loss of electrical power, the shut
down solenoid 73 will deenergize and spring 76 will move plunger 75
to the right, urging lever 71 to the right and causing the pilot
valve spool 21 and the fuel rack 15 to move to the fuel-shut-off
position. The bias force of shut down solenoid spring 76 is, of
course, sufficiently greater than the bias of torque motor spring
56 to enable such shut down of fuel.
The mechanical governor control 80 shown herein includes an
operator controlled throttle lever 81 pivoted about the axis of
shaft 82 and movable against spring seat 83. A speeder spring 84 is
confined between the speeder spring seats 83 and 85 and urges the
speeder spring seat 85 to the right. As shown in FIG. 2, rightward
movement of the speeder spring seat 85 is limited by engagement
with the plunger 86 of the solenoid 87. The plunger 86 has a
rounded end 88, and the speeder spring seat 85 has a tapered
surface 89.
The solenoid 87 is arranged so that, during normal operation of the
electronic engine control 60, it will be energized and its plunger
86 will be retracted to the position shown in FIG. 3, out of the
path of movement of the speeder spring seat 85. The mechanical
governor control 80 includes a riser member 90 movable in opposite
fuel-increasing and fuel-decreasing directions (shown in FIGS. 2
and 3 as being to the right and to the left, respectively). With
the solenoid 87 energized to retract its plunger 86, the speeder
spring 84 is free to bias the riser member 90 to the right so that
the thrust member 91 engages the arms 92 of the pivotal flyweights
93. The flyweights are driven around the axis of the shaft 94, in a
conventional manner and at a speed proportional to engine speed, so
that as the engine speed increases, the riser member 90 will move
in its fuel-decreasing direction, i.e. to the left in FIGS. 2 and
3, against the force of speeder spring 84. The riser member 90 has
an integral collar 96 with an annular groove 97 therearound.
A coupling means 98 is provided for connecting the mechanical
governor control 80 to the rack control member 16 to move the rack
control member 16 in a fuel-decreasing direction in response to
movement of the riser member 90 in its fuel-decreasing direction.
In the particular system shown, the coupling means 98 comprises a
control lever 99 mounted for pivotal movement about the fixed axis
of shaft 101, with one end 102 of the control lever 99 disposed in
the riser collar groove 97 and the other end 103 of the control
lever 99 being in the path of movement of the shoulder 104 on the
rack control member 16.
INDUSTRIAL APPLICABILITY
The hydraulic servo system 17 shown in FIGS. 1 and 2 operates as
follows. If rack control member 16 is moved to the left from the
position illustrated in the figures, it will urge the spring 37,
spring retainer 38, and the slidable pilot valve spool 21 to the
left. Such movement moves the valve spool recess 29 leftward
relative to the piston 19 so that the piston ports 31 communicate
with the piston ports 33 to allow oil to drain from the annular
chamber 26 to the left of the piston head 25. Oil entering the
cylinder 18 through the passage 22 and being pressurized by the
engine 13 will then effectively act upon the annular surface 27 of
the piston head 25, forcing the piston 19 and the fuel rack 15 to
move leftwardly in a fuel-increasing direction. When the piston 19
moves sufficiently to the left, so that the pilot valve recess 29
is blocked from communicating oil to the piston ports 33, fuel rack
movement will cease.
Movement of the rack control member 16 to the right will, by
engagement of the rack control member 16 against the retainer clip
39, move the pilot valve spool 21 to the right, so that the valve
spool recess 29 puts the piston ports 31 and 32 into communication
with each other. This enables pressurized oil to flow into the
annular chamber 26 so that the piston 19 and the fuel rack 15 are
forced rightwardly in a fuel-decreasing direction. When the piston
19 has moved sufficiently to the right so that fluid communication
between the piston ports 32 and spool recess 29 is blocked, the
piston 19 will assume a hydraulically balanced position until such
time as the pilot valve spool 21 is moved from its balanced
position relative to the piston 19.
In the fuel control system 10 of FIG. 1, the electronic engine
control 60 will process the various signals from the engine
operation sensors and make a determination as to the desired
position to which fuel rack 15 should be set for optimal maximum
amount of fuel injection under the existing conditions, without
having the engine exhaust exceed predetermined levels of smoke and
noxious emissions. The electronic control then outputs a
predetermined level of current to the torque motor 50 to move the
rack control member 16 to a desired position which is balanced by
spring 56. The hydraulic servo system 17 then functions, as
described above, to move the fuel rack 15 to the position
determined by the new position of the rack control member 16. The
actual position of the fuel rack 15, sensed by the rack position
sensor 62, is compared in the electronic engine control 60 with the
desired rack position, so that the output signal to the torque
motor 50 is maintained at a level sufficient to maintain the rack
control member 16 at the position necessary to keep the fuel rack
15 at the desired rack position.
The hydraulic forces on the pilot valve spool 21 are balanced at
all times so that only a relatively low level of force is required
from the torque motor 50 to move the rack control member 16 and to
hold such member at a desired position against the opposing force
of the spring 56.
In case of failure of the electronic engine control 60, the current
to torque motor 50 will urge its control lever 53 to rotate in a
counterclockwise direction. Such bias will move the rack control
member 16 to the right, causing the fuel rack 15 to move in its
fuel-decreasing direction. Such movement will continue until the
fuel rack 15 has moved to a fuel shut off position.
In the event of failure of the vehicle electrical system, or in the
event that the vehicle operator causes the shut-down solenoid 65 to
be disconnected from the electrical system, the deenergization of
the solenoid 65 will cause the pilot valve spool 21 to move to the
right, in turn causing the fuel rack 15 to be moved to a fuel shut
off position.
The operation of the fuel control system 70 when both the
electronic engine control 60 and the mechanical governor control 80
are functioning will depend upon the particular programming of the
electronic engine control used in the system.
For example, the electronic engine control 60 may be programmed to
function as a rack limit device, with primary control of rack
position being by the mechanical governor control 80. In such case,
the electronic engine control 60 could be programmed so that no
current is applied to the torque motor 50 as long as the fuel rack
15 is at a fuel delivering position less than the maximum position
determined by the electronic engine control. In such case, with no
current applied to the torque motor 50, its rotor 51 is free to
rotate and the spring 56 will urge the rack control member 16 to
the left so that the rack control shoulder 104 engages the end 103
of the control lever 99. Then, movement of the riser member 90, in
its fuel-increasing or fuel-decreasing direction, in response to
the opposing forces of the speeder spring 84 and the flyweights 93,
will be coupled to the rack control member 16 by control lever 99
to cause the rack control member 16 to move in a corresponding
fuel-increasing or fuel-decreasing direction.
In the event that the mechanical governor control 80 seeks to move
the fuel rack 15 in its fuel-increasing direction to a position
wherein the maximum allowable fuel delivery rate determined by the
electronic control will be exceeded, the electronic engine control
60 will output a signal to the torque motor 50 to generate
sufficient opposing torque to prevent further movement of the rack
control member 16 in its fuel-increasing direction. The end 103 of
the control lever 99 of the mechanical governor control 80 can
continue to move in its fuel-increasing direction because the
control lever end 103 is free to move leftwardly relative to the
shoulder 104 on the rack control member 16.
Subsequent movement of the end 103 of the control lever 99 in its
fuel-decreasing direction will enable the mechanical governor
control 80 to regain control of fuel rack movement when the fuel
rack position sought by the mechanical governor control 80 is less
than the maximum allowable limit set by the electronic engine
control 60.
Alternatively, the fuel control system 70 can function with the
electronic engine control 60 being programmed to provide primary
rack actuation and with the mechanical governor control 80 being
used as a rack limit device.
In such case, as long as the mechanical governor control moves its
control lever 99 to a position out of engagement with the shoulder
104 of the rack control member 16, rack position will be determined
by the degree of energization of the torque motor 50 by the
electronic engine control 60. If less fuel is desired, the torque
of the motor 50 will increase to move the rack control member 16 in
its fuel-decreasing direction. If more fuel is desired, the torque
of the motor 50 will be decreased so that the spring 56 will move
the rack control member 16 in its fuel-increasing direction. If the
electronic engine control 60 seeks a greater fuel rate than the
maximum amount allowed by the mechanical governor control, the
shoulder 104 of the rack control member 16 will engage the end 103
of control level 99 and further movement of the rack control member
16 will be prevented. The forces exerted on the control lever 99 by
the mechanical governor control 80 are sufficient to stop movement
of the rack control member 16 by the spring 56 in its
fuel-increasing direction when the shoulder 104 engages the control
lever 99.
The electronic engine control 60 will again take over control when
the electronic engine control calls for a rack position less than
that allowed by the mechanical governor control 80.
As may be seen, the dual control fuel control system of FIG. 2,
with both of the control levers 53 and 99 operating independently
of each other but both acting on the same rack control member 16,
enables a sure, smooth and simple switch over from mechanical
governing to electronic governing, and vice versa.
Additionally, the disclosed dual control system allows the same
hardware to be used for rack limiting or rack actuating by the
electronic engine control 60.
The dual control system of FIG. 2 is also advantageous in vehicle
use in that it enables a limited, limp-home operation of the engine
in case of failure of the electronic control, so that the operator
can move the vehicle to a service facility for repair.
If the electronic control fails, the torque motor 50 will be
deenergized and the spring 56 will bias the control lever 53 in a
fuel-increasing direction so that the shoulder 104 of the rack
control member 16 comes into engagement with the control lever 99.
At the same time, the solenoid 87 will be deenergized so that its
plunger 86 will move upwardly by a conventional internal spring
means (not shown).
If, at the time of electronic engine control failure, the speeder
spring seat 85 of the mechanical governor had been in a minimum
fuel delivery position to the left of the solenoid plunger 86, then
such plunger would be free to move fully upwardly so that it will
limit rightward movement of the speeder spring seat 85 therepast,
and thereby limit movement of the fuel rack 15 in its
fuel-increasing direction.
If the speeder spring seat 85 had been in a fuel delivery position
to the right of the solenoid plunger 86, an increase in engine
speed will cause the flyweights 93 to force the riser member 90 to
the left, in its fuel-decreasing direction. The rounded end 88 of
the solenoid plunger 86 will engage the tapered surface 89 of the
speeder spring seat 85 so that the plunger 86 will be cammed
downwardly as the speeder spring seat 85 is moved leftwardly by the
flyweight force. When the speeder spring seat 85 clears the plunger
86, the plunger will move upwardly to limit subsequent movement of
the speeder spring seat 85 in its fuel-increasing direction.
The engine may now be operated with the mechanical governor
functioning with a part load maximum fuel delivery setting to
provide a limp-home mode.
As is apparent from the preceding description, substantially the
same hardware is used for the electronic control of the rack
control member 16 in the fuel control system 10 of FIG. 1 or the
fuel control system 70 of FIGS. 2 and 3. As a consequence, the same
basic hardware components of the electronic control can be used in
a system wherein the fuel rack is controlled only by an electronic
engine control or in a dual control system wherein the fuel rack is
controlled electronically or mechanically.
The present invention is also very advantageous in that the torque
motor 50 can be programmed or positioned to exert torque in a
fuel-increasing direction or in a fuel-decreasing direction.
Likewise, the bias means 55 can easily be arranged to bias the rack
control member 16 in either a fuel-decreasing or a fuel-increasing
direction, or the bias may be omitted altogether. As a consequence,
the programming of the electronic engine control 60 may be widely
varied to provide different desired methods of control of fuel rack
positioning.
The present fuel control system 70 with its dual electronic and
mechanical control has a number of advantages in overall engine
control, in addition to those previously mentioned.
For example, the electronic engine control 60 can be easily
programmed to respond to an engine overspeed condition or to an
excessive ground speed condition and to cut back the fuel to the
engine from the amount called for by the mechanical governing
mechanism.
Further, in conventional fuel control systems, electro-mechanical
control valves and hydraulic servo cylinders are used to provide
rack limiting. The present dual control of the rack control member
16 eliminates the need for such components. Additionally, the
present invention also eliminates the need for the normally
required rack position limit stops. Such elimination of components,
of course, results in a desirable reduction in hardware cost.
Such elimination also reduces considerably the overall physical
size of the fuel rack control package, thereby reducing many
fitting problems in the design of new equipment and also enabling
easy conversion of an existing fuel control system having a
mechanical governor alone to a dual control system which also
incorporates electronic governing.
The present invention also has industrial applicability in that
with the electronic engine control 60 being used to set rack limit,
it is very difficult for the engine operator to tamper with the
rack limit setting, thus making the fuel control system more
acceptable to environmental regulatory agencies.
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